What was found
CREW REPORTED "NR 1 MCDU WENT BLANK AND HAD MINOR SMOKE" ON LOG PAGE 675912. THE CREW LATER STATED THAT IT WAS MORE OF AN ODOR OF SMOKE COINCIDING WITH THE MCDU GOING BLANK. THE ACFT WAS IN FLIGHT AT THE TIME, DECLARED AN EMERGENCY, AND RETURNED TO THE POINT OF DEPARTURE WITHOUT FURTHER INCIDENT. THE FAILED MCDU FROM FLIGHT 210, PN 4077880-982, SN 00062162 WAS ON ITS FIRST FLIGHT LEG INSTALLED IN THE ACFT. IT HAD BEEN INSTALLED AFT THE PREVIOUS FLIGHT HAD A FAILURE OF ITS MCDU WHILE ENROUTE, NO SMOKE OR OTHER ABNORMALITIES OTHER THAN THE MCDU BEING INOPERATIVE WERE REPORTED ON THAT FLIGHT LEG, LOG PAGE 675911. THE FIRST MCDU THAT FAILED WAS PN 4089740-961, SN 32199899. FINALLY, A 2ND REPLACEMENT MCDU WAS INSTALLED, PN 4077880-982, SN 31902805. ALL OPS WERE VERIFIED NORMAL AND THE ACFT OPERATES WITH OUT REPEAT DEFECT AT THIS TIME.